1. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display device and a method of fabricating the same and, more particularly, to an OLED display device and a method of fabricating the same having a dual structure of lower and upper lines connected through a contact hole to form a common power bus line and/or a cathode bus line.
2. Description of the Related Art
Recently, in order to reduce the heavyweight and large volume of a conventional display device such as a cathode ray tube, attentions have been directed to flat panel display devices such as a liquid crystal display device, an OLED display device, a plasma display panel, and so on.
However, since the liquid crystal display device is not a self-emitting device and instead is a light receiving device, it has a limitation in brightness, contrast, viewing angle, large-sized display, and so on. By contrast, the PDP is a self-emitting device, but it is heavier than the other flat panel display devices and has high power consumption, and its manufacturing method is complicated. On the other hand, since the OLED display device is a self-emitting device, it has an excellent viewing angle and contrast, and since it is not necessary to employ a backlight, it is possible to realize a lightweight and compact display device with reduce power consumption.
In addition, the OLED display device can be driven at a low direct current voltage, has a fast response time, and has a high impact resistance because, as a whole, it is made of a solid material. Also, the OLED display device has a broad usage temperature range, and its manufacturing method is simple.
Referring to FIG. 1, a light emitting portion 102 is disposed on a substrate 101. The light emitting portion 102 is composed of unit pixels including a first electrode, an organic layer having at least an organic emission layer, and a second electrode. A scan driver 103 and a data driver 104 are disposed at the peripheral portion of the light emitting portion 102 to transmit electrical signals to the unit pixels. A common power supply bus line 105 and a cathode bus line 106 are also disposed at the peripheral portion of the light emitting portion 102 to supply power. In addition, pads 107 for connecting the common power supply bus line 105 and the cathode bus line 106 with external devices are disposed on the substrate 101 together with the light emitting portion 102.
In FIG. 1, the common power supply bus line 105 and the cathode bus line 106 are made of wide (or broad) metal interconnections in order to supply sufficient power to the unit pixels without a high voltage drop.
However, the broad width of the conventional common power supply bus line and cathode bus line makes it difficult to increase an area of the light emitting portion.